Apparatus and method for reclaiming abrasive blasting material and screening device for separating abrasive blasting material

ABSTRACT

An apparatus for reclaiming abrasive blasting material comprises a prime mover, a vacuum pump and a separator unit for separating the abrasive blasting material in the contaminated abrasive blasting material from contaminants. The vacuum pick-up draws the contaminated abrasive blasting material. The separator unit includes a screening device for separating and reclaiming the abrasive blasting material. The screening device comprises a support member having a longitudinal axis and a transverse axis, and an endless flexible screen belt mounted to the support member so as to be movable along an endless closed loop in the direction of the longitudinal axis. The screen belt has a plurality of openings being sized to allow particles of the abrasive blasting material of a desired size to fall therethrough by gravity and to prevent the contaminants larger than the abrasive blasting material from falling therethrough.

CROSS-REFERENCE TO RELATED APPLICATION

This Application claims the benefit under 35 U.S.C. 119(e) of U.S.Provisional Patent Application Ser. No. 61/480,129 filed Apr. 28, 2011by Roden, J. R., which is hereby incorporated herein by reference in itsentirety and to which priority is claimed.

FIELD OF THE INVENTION

This present invention relates to devices and methods for cleaning,separating and reclaiming spent abrasive blasting material that havebeen employed during an abrasive blasting process in general and, moreparticularly, to a screening device for separating and recovering spentabrasive blasting material for reuse.

BACKGROUND OF THE INVENTION

Cleaning large metal surfaces with abrasive blasting material (abrasivegrit material) by abrasive blasting (or pressure blasting), such as bysandblasting, bead blasting, etc., is well known in the related art. Themost commonly used type of abrasive blasting media currently used issilica sand, fine glass beads, steel shot, steel grit, stainless steelshot, cut wire, grit or similar sized pellets, etc. It is possible torepeatedly use the same abrasive blasting material (or media) severaltimes, if the abrasive blasting material is properly cleaned betweeneach use.

One consequence of the abrasive blasting process on the abrasiveblasting materials resulting from high velocity impacting on steelsurfaces being cleaned causes them to abrade and generate contaminantssuch as dirt, paint, mill scale, and rust from the treated surface. Atthe same time a certain amount of fractured, fine abrasive particles(dust) is also produced.

Various types of devices for cleaning and reclaiming spent abrasiveblasting media are available in the related art. Typically, in such adevice, the used abrasive blasting media is vacuumed up and carried inan airstream to a cleaning and separating device. Lightweightcontaminants are removed by air-washing, while large particulatecontaminated material is separated by a separating device.

While known devices for cleaning and reclaiming spent abrasive blastingmedia have proven to be acceptable for various abrasive blasting mediacleaning and reclaiming applications, such devices are neverthelesssusceptible to improvements that may enhance their performance,applicability, cost and attractiveness. With this in mind, a need existsto develop an improved screening device and method for separating andrecovering spent abrasive blasting material for reuse that advances theart.

SUMMARY OF THE INVENTION

A first aspect of the invention provides a screening device forseparating and reclaiming abrasive blasting material from contaminants.The screening device comprises a support member having a longitudinalaxis and a transverse axis, and an endless flexible screen belt mountedto the support member so as to be movable along an endless closed loopin the direction of the longitudinal axis. The screen belt has aplurality of openings being sized so as to allow particles of theabrasive blasting material of a desired size to fall therethrough bygravity and to prevent contaminants larger than the abrasive blastingmaterial from falling therethrough by gravity.

According to a second aspect of the invention, an apparatus is providedfor reclaiming abrasive blasting material. The apparatus features aprime mover, vacuum pump powered by the prime mover, and a separatorunit for receiving contaminated abrasive blasting material via a vacuumpick-up and separating the abrasive blasting material in thecontaminated abrasive blasting material from contaminants larger thanthe abrasive blasting material. The vacuum pick-up fluidly is connectedto the vacuum pump to draw the contaminated abrasive blasting materialinto the vacuum pick-up. The separator unit includes a screening devicefor separating and reclaiming the abrasive blasting material. Thescreening device comprises a support member having a longitudinal axisand a transverse axis, and an endless flexible screen belt mounted tothe support member so as to be movable along an endless closed loop inthe direction of the longitudinal axis. The screen belt has a pluralityof openings sized so as to allow particles of the abrasive blastingmaterial of a desired size to fall therethrough by gravity and toprevent the contaminants larger than the abrasive blasting material fromfalling therethrough by gravity.

Other aspects of the invention, including apparatus, systems, methods,and the like which constitute part of the invention, will become moreapparent upon reading the following detailed description of theexemplary embodiments and viewing the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated in and constitute a part ofthe specification. The drawings, together with the general descriptiongiven above and the detailed description of the exemplary embodimentsand methods given below, serve to explain the principles of theinvention. In such drawings:

FIG. 1 is a side elevational view of a mobile apparatus for separationand recovery of spent abrasive blasting material according to anexemplary embodiment of the invention;

FIG. 2 is a top plan view of the mobile apparatus of FIG. 1;

FIG. 3 is a schematic view of a process of cleaning, separating andreclaiming spent abrasive blasting material employing the mobileapparatus of FIGS. 1 and 2;

FIG. 4 is a partial enlarged perspective view of a separator unit of themobile apparatus of FIGS. 1 and 2;

FIG. 5 is a partial enlarged perspective view of a screening device ofthe mobile apparatus of FIGS. 1 and 2;

FIG. 6A is a top plan view of the screening device of the mobileapparatus of FIGS. 1 and 2;

FIG. 6B is a front elevational view of the screening device of themobile apparatus of FIGS. 1 and 2;

FIG. 6C is a rear elevational view of the screening device of the mobileapparatus of FIGS. 1 and 2;

FIG. 7 is a bottom plan view of the screening device according to theexemplary embodiment of the invention showing a support member and adrive mechanism mounted to the support member;

FIG. 8 is a vertical cross-sectional view of the screening deviceaccording to the exemplary embodiment of the present invention takenalong the lines 8-8 in FIG. 6A;

FIG. 9 is a vertical cross-sectional view of the screening deviceaccording to the exemplary embodiment of the present invention takenalong the lines 9-9 in FIG. 6A;

FIG. 10 is an enlarged plan view of a fragment of an endless flexiblescreen belt of the screening device of FIG. 6A;

FIG. 11 is an enlarged plan view of a fragment of the endless flexiblescreen belt shown in circle “A” of FIG. 10; and

FIG. 12 is a partial exploded view of the endless flexible screen beltof FIG. 10.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS AND EXEMPLARY METHODS

Reference will now be made in detail to exemplary embodiments andmethods of the invention as illustrated in the accompanying drawings, inwhich like reference characters designate like or corresponding partsthroughout the drawings. It should be noted, however, that the inventionin its broader aspects is not limited to the specific details,representative devices and methods, and illustrative examples shown anddescribed in connection with the exemplary embodiments and methods.

This description of exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “horizontal,” “vertical,” “up,” “down,” “upper”, “lower”,“top” and “bottom” as well as derivatives thereof (e.g., “horizontally,”“downwardly,” “upwardly,” etc.) should be construed to refer to theorientation as then described or as shown in the drawing figure underdiscussion. These relative terms are for convenience of description andnormally are not intended to require a particular orientation. Termsconcerning attachments, coupling and the like, such as “connected” and“interconnected,” refer to a relationship wherein structures are securedor attached to one another either directly or indirectly throughintervening structures, as well as both movable or rigid attachments orrelationships, unless expressly described otherwise. The term“operatively connected” is such an attachment, coupling or connectionthat allows the pertinent structures to operate as intended by virtue ofthat relationship. Additionally, the word “a” as used in the claimsmeans “at least one”.

FIGS. 1-3 of the drawings illustrate an apparatus and a process forseparation and recovery (reclaiming, recycling) of used (or spent)abrasive blasting material (media) according to an exemplary embodimentof the present invention indicated generally by reference numeral 10.The apparatus 10 is an abrasive blasting material recycling system thatincludes vacuum recovery, classification, and air blasting units. Theapparatus 10 has four major subsystems: vacuum, classification,compressed air dryer, and blasting, and a control panel 11. According tothe exemplary embodiment of the present invention, the apparatus 10 is amobile apparatus in the form of a self-contained vehicle 12, such as atrailer, having one or more wheels and axle assemblies 14, one or moretelescopically extensible trailer stabilizer arms 15 that may extendfrom the trailer 12 and can be deployed therefrom to support andstabilize the trailer 12 during the operation of the mobile apparatus10. In other words, the components of the apparatus 10 according to theexemplary embodiment of the present invention are mounted on a singletrailer. Alternatively, the components of the mobile apparatus 10 can bemounted on a skid or multiple skids and trailers. Further alternatively,the apparatus 10 can be stationary, i.e. permanently mounted.

The apparatus 10 according to the exemplary embodiment of the presentinvention comprises a vacuum recovery unit 16 mounted on the trailer 12.The vacuum recovery unit 16 includes a vacuum storage hopper (bin) 18for receiving and storing (i.e., recovery of) spent or used, dirtyabrasive blasting material, such as abrasive grit. The spent dirty(i.e., contaminated) abrasive blasting material, generally denoted withthe reference numeral 22, is composed of the abrasive blasting material(media) 23 and various contaminants 24 including large contaminants(large trash items), paint chips and dust. It is desirable to remove thecontaminants 24 from the contaminated abrasive blasting material 22 andrecover clean abrasive blasting material 23 for reuse, as best shown inFIG. 3.

The contaminated abrasive blasting material 22 is initially deliveredinto the vacuum recovery unit 16 via a vacuum pick-up 17. The vacuumpick-up 17 is in fluid communication with a vacuum pump 28 selectivelypowered by a prime mover 29, i.e. a machine that transforms energy fromthermal, electrical or pressure energy to mechanical energy. In theexemplary embodiment of the present invention, the prime mover 29 is inthe form of an internal combustion engine, such as a diesel engine. Itwill be appreciated that any other type of prime mover, such as anelectric motor, is within the scope of the present invention. Both thevacuum pump 28 and the diesel engine 29 are mounted on the trailer 12.As illustrated in FIGS. 3 and 4, the vacuum recovery unit 16 furtherincludes a first (or primary) screening device 20 ₁ disposed in an upperportion of the vacuum storage hopper 18. The first screening device 20 ₁is provided with a screen having a plurality of holes, known as “mesh.”The primary screening device 20 ₁ is provided with the screen havingoversized screen holes for screening (separating) and reclaiming thecontaminated abrasive blasting material from large contaminants (orlarge trash items).

The contaminated abrasive blasting material from the vacuum pick-up 17is directed onto a front end 21 ₁₁ of the primary screening device 20 ₁,as shown in FIG. 3 of the drawings, through a feeding ramp 41 (shown inFIGS. 3 and 4). The recovered contaminated abrasive blasting materialfalls out of the air stream into the oversize screen of the primaryscreening device 20 ₁. The primary screening device 20 ₁ delivers thecontaminated abrasive blasting material from the front end 21 ₁₁ to arear end 21 ₁₂ thereof. The primary screening device 20 ₁ screens thecontaminated abrasive blasting material 22 by size while transportingthe contaminated abrasive blasting material 22 from the front end 21 ₁₁to the read end 21 ₁₂ thereof so as to allow only a desired size(including the particles of the abrasive blasting material 23) to falltherethrough by gravity and to prevent contaminants larger than thedesired size from falling therethrough by gravity. The contaminatedabrasive blasting material 22 (in this case, the mixture of the abrasiveblasting material and the remaining contaminates, separated by theprimary screening device 20 ₁ from the large contaminants) falls bygravity through the primary screening device 20 ₁ into a conical lowerportion 19 of the vacuum storage hopper 18. The large contaminants aredeposited into a large trash item container 25 from the rear end 21 ₁₂of the primary screening device 20 ₁ through a large item outlet 26. Thecontaminated abrasive blasting material 22 (with the remainingcontaminates but without the large contaminants) is then deposited intoa dirty grit transporter (container) 27.

The dirty (dusty) air is removed from the vacuum storage hopper 18 to avacuum dust collector 42 where the air is filtered by primary filters 44and secondary filters 45, then passes through a vacuum tube 46 to thevacuum pump 28, where it is discharged into the atmosphere. The dustremoved from the dirty air is deposited into a dust container 50 througha double dump dust discharge 49, shown in FIG. 3.

The apparatus 10 further comprises a classifier unit 30 mounted on thetrailer 12 and in fluid communication with the vacuum recovery unit 16.The classifier unit 30 includes a dust separator 32 with an air washintake 33, a second (or secondary) screening device 20 ₂ disposed in anupper portion of classifier bin 34, and a magnetic drum separator 36disposed downstream of the secondary screening device 20 ₂. Theclassifier bin 34 has a funnelled lower portion 35 with an outletopening facing the magnetic separator 36. The magnetic separator 36 isdisposed in a separator bin 38 located beneath (downstream) theclassifier bin 34. The separator bin 38 includes a contaminant section39 ₁ and an uncontaminated section 39 ₂.

The second screening device 20 ₂, like the first screening device 20 ₁,is provided with a screen having a plurality of holes, known as “mesh.”The second screening device 20 ₂ screens (separating) and reclaims thecontaminated abrasive blasting material 22 from the remainingcontaminants 24. It should be noted that the size of the screen mesh ofthe secondary screening device 20 ₂ is smaller than the size of thescreen mesh of the primary screening device 20 ₁. Otherwise, the firstscreening device 20 ₁ and the second screening device 20 ₂ aresubstantially structurally identical.

After screening through the primary screening device 20 ₁, the recoveredcontaminated abrasive blasting material 22 from the dirty grittransporter 27 is transported to the classifier unit 30 where it isde-dusted in the air wash of the dust separator 32, screened again inthe secondary screening device 20 ₂, passes over the magnetic drumseparator 36, and is then transferred to a recycled grit storage hopper40.

Specifically, the contaminated abrasive blasting material 22 from thedirty grit transporter 27 is fed onto a front end 21 ₂₁ of the secondaryscreening device 20 ₂, as shown in FIG. 3 of the drawings, through adelivery passage 31. The secondary screening device 20 ₂ delivers thecontaminated abrasive blasting material 22 from the front end 21 ₂₁ to arear end 21 ₂₂ thereof. The secondary screening device 20 ₂ screens thecontaminated abrasive blasting material 22 by size while transportingthe contaminated abrasive blasting material 22 from the front end 21 ₂₁to the read end 21 ₁₂ thereof so as to allow material of only a desiredsize (such as the particles of the abrasive blasting material 23) tofail therethrough by gravity and to prevent contaminants larger than thedesired size from falling therethrough.

The contaminated abrasive blasting material 22 (in this case, themixture of the abrasive blasting material and the remainingcontaminates, separated by the secondary screening device 20 ₂ from themedium-size contaminants) falls by gravity through the secondaryscreening device 20 ₂ into the funnel-shaped lower portion 35 of theclassifier bin 34. The medium-size contaminants, such as paint chips,are transported to and deposited into the contaminant section 39 ₁ ofthe separator bin 38. The contaminated abrasive blasting material 22(with the remaining contaminates but without the medium-sizecontaminants) is then deposited into the lower portion 35 of theclassifier bin 34.

The magnetic separator 36 comprises a drum at least a portion of whichis magnetized. Consequently, as the contaminated abrasive blastingmaterial 22 is supplied to the magnetic separator 35, the magneticcontaminants 24 are separated therefrom and conveyed to the contaminantsection 39 ₁ of the magnetic separator bin 38, while the reclaimed(recycled), clean abrasive blasting material 23 is fed to theuncontaminated section 39 ₂ of the magnetic separator bin 38. Therecycled abrasive blasting material 23 (substantially without thecontaminants, i.e., with negligible amount of contaminants, such asdust) is then deposited into the recycled grit storage hopper 40.

The dirty (dusty) air from the dust separator 32 is removed to a recyclecollector 52 (using vacuum created by a recycle blower 54), where theair is filtered by filters 55, then passes to the vacuum dust collector42 where the air is filtered, then discharged into the atmosphere. Thedirty (dusty) air from the contaminant section 39 ₁ of the magneticseparator bin 38 is removed from the contaminant section 39 ₁ of themagnetic separator bin 38 to the vacuum dust collector 42 where the airis filtered by the primary filters 44 and secondary filters 45, thenpasses to the vacuum pump 28 where it is discharged into the atmosphere.The dust removed from the dirty air is deposited into a dust container50, as best shown in FIG. 3.

The recycled (reclaimed) abrasive blasting material 23 is thentransported to a blast pot unit 58 and deposited into a recycled gritstorage hopper 60. The dirty (dusty) air from the recycled grit storagehopper 60 is removed to the recycle collector 52 where the air isfiltered, then passes to the vacuum dust collector 42 where the air isfiltered again, then discharged into the atmosphere. The blast pot unit58 further includes a plurality of blast pots 92. The recycled(reclaimed) abrasive blasting material 23 stored in the recycled gritstorage hopper 60 is loaded in to the blast pots 92 as needed.Compressed air from an external air compressor(s) passes through acompressed air dryer 94 where it is prepared for use in the blast potunit 58 to propel the recycled abrasive blasting material 23 throughhoses 96, ere it is directed at steel and other substrates forcorrosion, paint, and contaminate removal. The compressed air dryer 94is connected to the external air compressor(s) via a compressed airconnector 97. Before entering the compressed air dryer 94, thecompressed air passes through a compressed air intercooler 98, which isprovided with a cooling fan unit 100.

After being blasted, the spent abrasive blasting material 22 is vacuumedback into the vacuum recovery unit 16 to start the recycling processagain.

As noted above, the first (primary) screening device 20 ₁ and the second(secondary) screening device 20 ₂ are substantially structurallyidentical and differ primarily in physical size and mesh size of thescreens. In view of the structural similarities of the first and secondscreening device 20 ₁ and 20 ₂, and in the interest of simplicity, thefollowing discussion will use a reference numeral without a subscriptnumber to designate both of the screening devices. For example, thereference numeral 20 will be used when generically referring to thescreening devices 20 ₁ and 20 ₂ rather than reciting both referencenumerals. Accordingly, because the screening devices 20 ₁ and 20 ₂ aresubstantially identical in design, only one of the screening devices 20₁ and 20 ₂ will be described in detail hereinbelow. As best illustratedin detail in FIGS. 6A-9, the screening device 20 comprises a supportmember 62 having a longitudinal axis X-X and a transverse axis Y-Yperpendicular to the longitudinal axis X-X, an endless flexible screenbelt 70 mounted to the supporting member 62 so as to be movable about anendless closed loop in the direction of the longitudinal axis X-Xdefining the travel direction of the screen belt 70, and a drivemechanism mounted to the support member 62 for driving the screen belt70 along the endless closed loop.

In the exemplary embodiment of FIGS. 5-9, the support member 62 is inthe form of a frame including two opposite longitudinally extending(i.e., in the direction of the longitudinal axis X-X) side plates 63 aand 63 b, interconnected by a transverse end plate 63 c extending in thedirection of the transverse axis Y-Y. The frame 62 further comprises oneor more bars 64 transversely extending between the longitudinal sideplates 63 a and 63 b. It will be appreciated that the support member 62may be of any other appropriate form and configuration so as to movablysupport the endless flexible screen belt 70. The support member 62further comprises opposite mounting members 65 provided for securing thescreening device 20 within the vacuum storage hopper 18, as best shownin FIGS. 1-4.

The endless flexible screen belt 70 is in the form of an endlessflexible wire mesh belt that includes a plurality of substantiallyidentical, single-piece, interconnected spiral wire members (wire coils)72 each extending in the direction of the transverse axis Y-Y andarranged parallel to each other. Each of the spiral wire members 72includes a plurality of spiral (helical) windings 73. According to theexemplary embodiment of the present invention shown in FIG. 8, thespiral windings 73 of each of the wire members 72 have substantiallyoval cross-section extending in the direction of the longitudinal axisX-X. Each of the wire members 72 includes a plurality of opposite,substantially semi-circular end portions 73 e facing each other. Asfurther illustrated in FIGS. 8-12, the end portions 73 e of the adjacentspiral wire members 72 overlap in the direction of the longitudinal axisX-X and are spaced from each other in the direction of the transverseaxis Y-Y. Furthermore, the spiral wire members 72 are preferably made ofcarbon steel of round cross-section. It should be noted that any otherappropriate material, such as strong polyester, or cross-section arewithin the scope of the present invention.

The wire mesh belt 70 further comprises a plurality of connecting rodmembers 74 extending in the direction of the transverse axis Y-Y andspaced from one another in the direction of the longitudinal axis X-X soas to be arranged parallel to each other. The connecting rod members 74are preferably made of low carbon steel and have a nominal diameter of0.228 inches. As illustrated in detail in FIGS. 6A-6B and 8-12, each ofthe connecting rod members 74 extends through two adjacent spiral wiremembers 72 so as to interconnect the end portions 73 e of the twoadjacent spiral wire members 72. In the exemplary embodiment of thepresent invention the adjacent wire members 72 are spirally (helically)wound in opposite directions. The wire members 72 are preferably madefrom 12 gauge low carbon steel, and have a nominal diameter of 0.105inches. Furthermore, the screen belt 70 defines a plurality of openings73′ sized to allow particles of the abrasive blasting material of adesired size to fall therethrough by gravity and to prevent thecontaminants larger than the abrasive blasting material from fallingtherethrough by gravity. The openings 73′ are preferably 0.145 incheswide by about 0.35 inches long, although they may be larger or smallerdepending upon the abrasive being used. It should be understood thatopen spaces 76 formed in the spiral wire members 72 between the spacedconnecting rod members 74 define the screen openings of the screen belt70. Those skilled in the art will realize that by manipulating the pitchof the spiral wire members 72, the size of the screen openings 76 (themesh) can be adjusted as required depending on the abrasive blastingmaterial employed. The term “pitch” is commonly defined in the art asthe distance from a center of one spiral winding 73 to the center of theadjacent spiral winding 73 of the same spiral wire member 72.

The drive mechanism of the screening device 20 comprises a pair ofseparate, synchronously driven endless power transmitting members in theform of link drive chains 78 according to the exemplary embodiment ofthe present invention. The drive chains 78 are disposed on transverselyopposite sides of the screen belt 70 so as to extend in parallel spacedrelationship along opposite transverse edges of the screen belt 70 inthe direction of the longitudinal axis X-X, and interconnected by theconnecting rod members 74, a pair of separate, synchronously driven,coaxial drive sprockets 80 and a pair of separate, synchronously driven,coaxial driven sprockets 82 each drivingly engaging one of the linkdrive chains 78. In other words, each of the synchronously drivenendless driving chains 12 runs over and between two pairs of the coaxialdrive and driven sprockets 80, 82. As illustrated in detail in FIGS. 6A,9 and 10, the link drive chains 78 are fixed or attached to oppositedistal ends of the connecting rod members 74 of the screen belt 70 byany appropriate means known in the art so that the movement of the linkdrive chains 78 in the direction of the longitudinal axis X-X impartsthe corresponding movement of the screen belt 70 in the same direction.Moreover, each of the drive sprockets 80 is rotatably mounted to thesupport member 62 though a drive shaft 81, while each of the drivensprockets 82 is rotatably mounted to the support member 62 though adriven shaft 83.

As further illustrated in detail in FIGS. 6A and 7-9, the drivemechanism of the screening device 20 also comprises a drive motor 84provided for rotating the drive shaft 81 through a gearbox 85. In otherwords, the endless link drive chains 78 are synchronously driven in thedirection of the longitudinal axis X-X by the motor 84 through the drivesprockets 80. Moreover, the screen belt 70 is rotatably mounted to thesupport member 62 through the drive and driven sprockets 80, 82 of thedrive mechanism and is driven in the direction of the longitudinal axisX-X by the motor 84 through the drive sprockets 80 and the endless linkdrive chains 78. According to the exemplary embodiment of the presentinvention, the motor 84 is an electric motor. Alternatively, anyappropriate motor, such as a hydraulic motor or pneumatic motor, can beused with or without the gearbox.

In operation, the contaminated abrasive blasting material from thevacuum pick-up 17 is directed into the screening device 20, as shown inFIG. 3 of the drawings, through a feeding ramp 21 that delivers thecontaminated abrasive blasting material to a front end 70 _(f) of thescreen belt 70 of the screening device 20. As the screen belt 70 isdriven along an endless closed loop in the direction of the longitudinalaxis X-X by the drive motor 84, the contaminated abrasive blastingmaterial deposited to the screen belt 70 travels in the travel directionT toward a rear end 70 _(r) thereof. During the travel from the frontend 70 f toward the rear end 70 _(r) of the screen belt 70, mixture 22of the particles of the abrasive blasting material and the remainingcontaminates of a desired size fall through the screen openings 76 inthe screen belt 70 by gravity into the funnel-shaped lower portion 19 ofthe vacuum storage hopper 18, while large contaminants, separated fromthe mixture 22, are deposited into the large trash item container 25through the large item outlet 26. The screening device 20 is furtherprovided with skirts 68 inclined toward the screen belt 70 and extendingin parallel spaced relationship along opposite transverse edges thereofin the direction of the longitudinal axis X-X in order to keep thecontaminated abrasive blasting material 22 on the moving screen belt 70.

As further illustrated in detail in FIGS. 5 and 7, the screening device20 also includes drive and driven support rollers 86 and 88,respectively, coaxially arranged between the drive and driven sprockets80 and 82, respectively, for supporting a central portion (in thedirection of the transverse axis Y-Y) of the screen belt 70.Specifically, the drive support roller 86 is non-rotatably mounted tothe drive shaft 81 so as to be rotatable relative to the support member62 along with the drive sprockets 80, while the driven support roller 88is non-rotatably mounted to the driven shaft 83 so as to be rotatablerelative to the support member 62 along with the driven sprockets 82.Moreover, the support member 62 of the screening device 20 furtherincludes support flanges 66 provided for supporting opposite transverseedges of the screen belt 70.

The foregoing description of the exemplary embodiments of the presentinvention has been presented for the purpose of illustration inaccordance with the provisions of the Patent Statutes. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obvious modifications or variations are possible in fight ofthe above teachings. The embodiments disclosed hereinabove were chosenin order to best illustrate the principles of the present invention andits practical application to thereby enable those of ordinary skill inthe art to best utilize the invention in various embodiments and withvarious modifications as are suited to the particular use contemplated,as long as the principles described herein are followed. Thus, changescan be made in the above-described invention without departing from theintent and scope thereof. It is also intended that the scope of thepresent invention be defined by the claims appended thereto.

What is claimed is:
 1. A screening device for separating and reclaimingabrasive blasting material from contaminants, said screening devicecomprising: a support member having a longitudinal axis and a transverseaxis; and an endless flexible screen belt mounted to said support memberso as to be movable along an endless closed loop in the direction ofsaid longitudinal axis; said screen belt having a plurality of openings,said screen openings being sized to allow particles of said abrasiveblasting material of a desired size to fall therethrough by gravity andto prevent said contaminants larger than said abrasive blasting materialfrom falling therethrough by gravity; said screen belt being in the formof an endless flexible wire mesh belt comprising a plurality ofinterconnected spiral wire members extending in the direction of saidtransverse axis and arranged parallel to each another; said wire meshbelt further comprising a plurality of connecting rod members extendingin the direction of said transverse axis and being spaced from oneanother in the direction of said longitudinal axis; each of saidconnecting rod members extending through two adjacent spiral wiremembers so as to interconnect said two adjacent spiral wire members;open spaces formed in said spiral wire members between said spacedconnecting rod members defining said screen openings of said screenbelt.
 2. The screening device as defined in claim 1, further comprisinga drive mechanism mounted to said support member for driving said screenbelt along said endless closed loop.
 3. The screening device as definedin claim 2, wherein said drive mechanism comprises an endless flexiblepower transmitting member attached to said screen belt so that themovement of said endless flexible power transmitting member imparts thecorresponding movement of said screen belt.
 4. The screening device asdefined in claim 3, wherein said endless flexible power transmittingmember is an endless flexible drive chain attached to said screen beltso that the movement of said drive chain imparts the correspondingmovement of said screen belt.
 5. The screening device as defined inclaim 4, wherein said endless flexible drive chain extends in thedirection of said longitudinal axis.
 6. The screening device as definedin claim 4, wherein said drive mechanism further comprises at least onedrive sprocket rotatably mounted to said support member and drivinglyengaging said link drive chain.
 7. The screening device as defined inclaim 6, wherein said drive mechanism further comprises a motor providedfor driving said at least one drive sprocket.
 8. The screening device asdefined in claim 1, wherein each of said spiral wire members has an ovalconfiguration in the direction of said longitudinal axis.
 9. Anapparatus for reclaiming abrasive blasting material, said apparatuscomprising: a prime mover; a vacuum pump powered by said prime mover;and a separator unit for receiving said contaminated abrasive blastingmaterial via a vacuum pick-up and separating said abrasive blastingmaterial in said contaminated abrasive blasting material fromcontaminants larger than said abrasive blasting material; said vacuumpick-up fluidly connected to said vacuum pump to draw said contaminatedabrasive blasting material into said vacuum pick-up; said separator unitincluding a screening device for separating and reclaiming said abrasiveblasting material, said screening device comprising: a support memberhaving a longitudinal axis and a transverse axis; and an endlessflexible screen belt mounted to said support member so as to be movablealong an endless closed loop in the direction of said longitudinal axis;said screen belt having a plurality of openings, said screen openingsbeing sized to allow particles of said abrasive blasting material of adesired size to fall therethrough by gravity and to prevent saidcontaminants larger than said abrasive blasting material from fallingtherethrough by gravity; said screen belt being in the form of anendless flexible wire mesh belt comprising a plurality of interconnectedspiral wire members extending in the direction of said transverse axisand arranged parallel to each another; said wire mesh belt furthercomprising a plurality of connecting rod members extending in thedirection of said transverse axis and being spaced from one another inthe direction of said longitudinal axis; each of said connecting rodmembers extending through two adjacent spiral wire members so as tointerconnect said two adjacent spiral wire members; open spaces formedin said spiral wire members between said spaced connecting rod membersdefining said screen openings of said screen belt.
 10. The apparatus asdefined in claim 9, wherein said screening device further comprises adrive mechanism mounted to said support member for driving said screenbelt along said endless closed loop.
 11. The apparatus as defined inclaim 10, wherein said drive mechanism comprises an endless flexiblepower transmitting member attached to said screen belt so that themovement of said endless flexible power transmitting member imparts thecorresponding movement of said screen belt.
 12. The apparatus as definedin claim 11, wherein said endless flexible power transmitting member isan endless flexible drive chain attached to said screen belt so that themovement of said drive chain imparts the corresponding movement of saidscreen belt.
 13. The apparatus as defined in claim 12, wherein saidendless flexible drive chain extends in the direction of saidlongitudinal axis.
 14. The apparatus as defined in claim 12, whereinsaid drive mechanism further comprises at least one drive sprocketrotatably mounted to said support member and drivingly engaging saidlink drive chain.
 15. The apparatus as defined in claim 12, wherein saiddrive mechanism further comprises a motor provided for driving said atleast one drive sprocket.
 16. The apparatus as defined in claim 9,wherein each of said spiral wire members has an oval configuration inthe direction of said longitudinal axis.
 17. The apparatus as defined inclaim 9, further comprising a vehicle having at least one axle assemblywith wheels or at least one skid such that said prime mover, said vacuumpump and said separator unit are mounted on said vehicle.